The TENS machine is a device for transmitting electrical energy through the skin to the nerves, to try and relieve pain. The initials TENS stand for transcutaneous electrical nerve stimulation.

There are a number of different types of TENS machines, some are quite large whilst others are small and portable, but all work on the same principle. They all use electricity, from the mains or from batteries, to produce electrical impulses which pass through wires to two electrodes placed on the skin. The electrodes are silicone rubber pads containing fine particles of carbon which transmit the impulse to the skin.

The treatment itself is painless and may last anywhere from a few minutes to hours and can be continued for as long as it is helpful (although there is tendency for the treatment to become less effective after several months).

The benefit is often not immediate and it may take some days to find the most effective position for the electrodes. When the treatment does work people often say that it changes the pain to a much more comfortable sensation of buzzing or humming TENS machines are not suitable for some people with heart pacemakers. It has also been said that they are less effective for people taking morphine or other strong pain killers but this is not universally true.

TENS machines tend to work best on parts of the body where there is a good cushion of tissue between the skin and any underlying bone.

There are differing reports about the value of TENS machines in controlling cancer pain. Some doctors have said they don't think they help whilst others claim they are very useful. For people who do have pain from cancer that is not well controlled with other treatments it is always worthwhile discussing it with their doctors to see whether they think a TENS machine could help.